Today, there exists a wide array of mechanical door locks which can be unlocked by thin, credit-card sized magnetic keys. Operation of these types of locks are based on the principle of using magnetic card keys which are encoded with a unique pattern of magnetic spots to unlock a mechanical door lock. Provided that a correctly encoded magnetic card key is inserted into its matching door lock, the magnetic spots on the card key align with the locking pins that normally holds a moveable slide in a locked position. These magnetic spots will magnetically repel the locking pins out of the holes of a locking plate, thereby permitting the slide to be moved to an unlocked position. If an incorrect key is inserted, its magnetic spots will not be of the proper pattern and/or polarity to cause the locking pins to be repelled to the unlocked state. One example of such a magnetic key locking system is described in U.S. Pat. No. 4,312,198.
The attractiveness of using magnetic key locks is due to the fact that the combination of a particular lock can be readily altered. Thereby, there is no need to physically remove and replace an existing door lock. Instead, one only needs to change its combination. In this manner, when a guest departs a hotel, the combination for that particular room's lock can be changed, and an arriving guest is provided with a correctly encoded key. Furthermore, the magnetic credit keys can be programmed to provide for different access privileges. For instance, a janitor might be issued a key granting access to certain areas, whereas a vice-president can have a key that provides access to more sensitive areas.
In the past, the magnetic card keys were encoded with their respective magnetic spot patterns at the factory. When a need to change the coding of a key, the key was sent back to the factory. This process was unwieldy, time-consuming, and unduly restrictive. In an effort to provide for greater flexibility and faster turn-around time, a manually operated hand-held encoder was developed. One such hand-held encoder is described in U.S. Pat. No. 4,128,851.
Typically, the card key was first inserted into a template. The template had a number of holes punched out which specifies the magnetic spot pattern. The holes were usually color coded to inform the operator of the proper polarity for each of the magnetic spots. The human operator would then insert the tip of the hand-held encoder into the first hole of the template. Next, the operator would flip a switch to place the encoder at the proper polarity specified by the template. Thereupon, the operator would depress a trigger on the encoder to initiate its electronics for magnetically encoding that spot. The operator would repeat this procedure for each and every one of the numerous spots on the card key.
Although this hand-held encoder allows the card keys to be encoded on-site, it has several drawbacks. Foremost, this type of encoder is extremely labor-intensive and time-consuming. And besides being tedious, this encoding process is also very error-prone. Just one mistake in the coding of a single magnetic spot will render that key inoperative. These problem are compounded when many keys need to be re-encoded.
Thus, there exists a need for an apparatus and method for encoding the card keys on-site which is efficient, quick, reliable, and cost-effective.